The present invention relates to a charge storage device and a method of manufacture thereof.
The invention has been developed primarily for use with the electrochemical charge storage devices such as supercapacitors and will be described hereinafter with reference to that application. It will be appreciated that supercapacitors are designated by terms such as ultra capacitors, electric double layer capacitors and electrochemical capacitors, amongst others, all of which are included within the term xe2x80x9csupercapacitorxe2x80x9d as used within this specification.
It is known to mass produce supercapacitors that have specific operational characteristics that fall within well defined ranges. Although mass production is advantageous from a cost point of view, there is an inherent lack of flexibility. That is, if the desired characteristics of a supercapacitor for a particular application fall outside the commonly available ranges a compromise solution is required. An alternative is to produce the desired supercapacitor as a one off or small run. The costs of this latter alternative are often prohibitive and, as such, rarely pursued.
Known supercapacitors generally find application in power supplies such as uninternuptible power supplies for computers or backup power supplies for volatile memory. Accordingly, it has been common to optimise these supercapacitors for high energy density, low self-discharge rates, and low cost.
More recently it has been thought that supercapacitors are theoretically applicable to high power pulsed applications. Indeed, some attempts have been made to adapt such supercapacitors as short term current sources or sinks. Examples of such applications include internal combustion engine starting, load power leveling for hybrid vehicles and a variety of pulsed communication systems. However, the success of these supercapacitors has been limited by factors such as a high equivalent series resistance, among others. For example, some prior art double layer capacitors make use of button cell or spiral wound technology. These, in turn, fall generally in one of two groups, the first group being concerned with high power applications and the second with low power applications. For the second group, but not the first, it has been possible to obtain high energy densities.
The first and second groups are broadly defined by the type of electrolyte used, those being aqueous and non-aqueous respectively. This is predominantly due to the lower resistance inherently offered by aqueous electrolytes which makes it better suited to high power, and hence high current, applications. That is, the low resistance results in lower I2R losses for aqueous electrolytes. The trade off, however, is that for these aqueous electrolytes the voltage that can be applied across a capacitive cell is extremely limited.
The second group of prior art double layer capacitors suffers the converse disadvantages. That is, while they provide a greater voltage window, which improves the available energy density, they also have had high internal resistances which make them unsuitable to the high power applications.
It is an object of the present invention, at least in the preferred embodiments, to overcome or substantially ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative.
According to a first aspect of the invention there is provided a charge storage device including:
a first electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric FOM of the device is greater than about 2.1 Watts/gram.
Preferably, the gravimetric FOM of the device is greater than about 2.5 Watts/gram. More preferably, the gravimetric FOM of the device is greater than about 3 Watts/gram. Even more preferably, the gravimetric FOM of the device is greater than about 3.5 Watts/gram. In some embodiments, the gravimetric FOM of the device is greater than about 5 Watts/gram.
More preferably, the first electrode and the second electrode form a capacitive cell and the device includes a plurality of the cells electrically connected in parallel and disposed within the package. In other embodiments, however, the cells are connected in series. In still further embodiments a combination of series and parallel connects are utilized. It will be appreciated that series connections allow the cells to be applied to higher voltage applications, while parallel connections allow the cells to provide a higher combined capacitance for the device. The ease at which these different connections are accommodated by the invention means that preferred embodiments are applicable to a wide variety of tasks ranging from high power systems to low power systems.
In a preferred form, the maximum operating voltage of the or each capacitive cell is less than about 4 Volts. More preferably, the maximum operating voltage of the or each capacitive cell is less than about 3.5 Volts. Even more preferably, the maximum operating voltage of the or each capacitive cell is less than about 3 Volts.
Preferably, the first electrode and the second electrode include a first carbon coating and a second carbon coating respectively wherein the surface area of carbon used in the coatings is greater than 20 m2/gram.
According to a second aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
disposing a second electrode in opposition to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing within a sealed package the electrodes, the separator and an electrolyte, wherein the electrodes are immersed in the electrolyte; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric FOM of the device is greater than about 2.1 Watts/gram.
Preferably, the gravimetric FOM of the device is greater than about 2.5 Watts/gram. More preferably, the gravimetric FOM of the device is greater than about 3 Watts/gram. Even more preferably, the gravimetric FOM of the device is greater than about 3.5 Watts/gram. In some embodiments, the gravimetric FOM of the device is greater than about 5 Watts/gram.
More preferably, the first electrode and the second electrode form a capacitive cell and the device includes a plurality of the cells electrically connected in parallel and disposed within the package. In other embodiments, however, the cells are connected in series. In still further embodiments a combination of series and parallel connects are utilised.
In a preferred form, the maximum operating voltage of the or each capacitive cell is less than about 4 Volts. More preferably, the maximum operating voltage of the or each capacitive cell is less than about 3.5 Volts. Even more preferably, the maximum operating voltage of the or each capacitive cell is less than about 3 Volts.
Preferably, the first electrode and the second electrode include a first carbon coating and a second carbon coating respectively wherein the surface area of carbon used in the coatings is greater than 20 m2/gram.
According to a third aspect of the invention there is provided a charge storage device including:
a fist electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the volumetric FOM of the device is greater then about 3.2 Watts/cm3.
Preferably, the volumetric FOM of the device is greater than about 4 Watts/cm3. More preferably, the volumetric FOM of the device is greater than about 5 Watts/cm3. Even more preferably, the volumetric FOM of the device is greater than about 7 Watts/cm3. In some embodiments, the volumetric FOM of the device is greater than about 8 Watts/cm3.
More preferably, the first electrode and the second electrode form a capacitive cell and the device includes a plurality of the cells electrically connected in parallel and disposed within the package. In other embodiments, however, the cells are connected in series. In still further embodiments a combination of series and parallel connects are utilised. It will be appreciated that series connections allow the cells to be applied to higher voltage applications, while parallel connections allow the cells to provide a higher combined capacitance for the device. The ease at which these different connections are accommodated by the invention means that preferred embodiments are applicable to a wide variety of tasks ranging from high power systems to low power systems.
In a preferred form, the maximum operating voltage of the or each capacitive is less than about 4 Volts. More preferably, the maximum operating voltage of the or each capacitive cell is less than about 3.5 Volts. Even more preferably, the maximum operating voltage of the or each capacitive cell is less than about 3 Volts.
Preferably, the first electrode and the second electrode include a first carbon coating and a second carbon coating respectively wherein the surface area of carbon used in the coatings is greater than 20 m2/gram.
According to a fourth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
disposing a second electrode in opposition to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing within a sealed package the electrodes, the separator and an electrolyte, wherein the electrodes are immersed in the electrolyte; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the volumetric FOM of the device is greater than about 3.2 Watts/cm3.
Preferably, the volumetric FOM of the device is greater than about 4 Watts/cm3. More preferably, the volumetric FOM of the device is greater than about 5 Watts/cm3. Even more preferably, the volumetric FOM of the device is greater than about 7 Watts/cm3. In some embodiments, the volumetric FOM of the device is greater than about 8 Watts/cm3.
According to a fifth aspect of the invention there is provided a charge storage device including:
a first electrode having a first conductive substrate;
a first carbon layer supported on the first substrate and being formed from a carbon having a surface area greater than 400 m2/gram;
a second electrode having a second conductive substrate;
a second carbon layer supported on the second substrate and being formed from a carbon having a surface area greater than 400 m2/gram;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an organic electrolyte in which the electrodes are immersed, wherein the first and second layers are opposed and spaced apart; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the volumetric FOM of the device is greater than about 1.1 Watts/cm3.
According to a sixth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode having a first conductive substrate;
supporting a first carbon layer on the first substrate, the first layer being formed from a carbon having a surface area greater than 400 m2/gram;
providing a second electrode having a second conductive substrate;
supporting a second carbon layer on the second substrate, the second layer being formed from a carbon having a surface area greater than 400 m2/gram;
disposing a porous separator between the electrodes;
containing the electrodes, the separator and an organic electrolyte in which the electrodes are immersed in a sealed package, wherein the first and second layers are opposed and spaced apart; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals both extend from the package to allow external electrical connection to the respective electrodes, and wherein the volumetric FOM of the device is greater than about 1.1 Watts/cm3.
According to a seventh aspect of the invention there is provided a charge storage device including:
a first electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the response time (To) of the device is less than about 0.09 seconds.
Preferably, To is less than about 10xe2x88x922 seconds. More preferably, To is less than about 10xe2x88x923 seconds. Even more preferably, To is less than about 10xe2x88x924 seconds. In some embodiments, To is less than about 5xc3x9710xe2x88x925 seconds.
According to an eighth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
providing a second electrode being opposed to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing the electrodes, the separator and an electrolyte in which the electrodes are immersed a sealed package; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, is wherein the response time (To) of the device is less than about 0.09 seconds.
Preferably, To is less than about 10xe2x88x922 seconds. More preferably, To is less than about 10xe2x88x923 seconds. Even more preferably, To is less than about 10xe2x88x924 seconds. In some embodiments, To is less than about 5xc3x9710xe2x88x925 seconds.
According to a ninth aspect of the invention there is provided a charge storage device including:
a first electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric power maximum of the device is greater than about 12.5 Watts/gram.
Preferably, the gravimetric power maximum of the device is greater than about 15 Watts/gram. More preferably, the gravimetric power maximum of the device is greater than about 17 Watts/gram. Even more preferably, the gravimetric power maximum of the device is greater than about 20 Watts/gram. In some embodiments the gravimetric power maximum of the device is greater than about 26 Watts/gram.
According to a tenth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
disposing a second electrode in opposition to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing within a sealed package the electrodes, the separator and an electrolyte, wherein the electrodes are immersed in the electrolyte; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric power maximum of the device is greater than about 12.5 Watts/gram.
Preferably, the gravimetric power maximum of the device is greater than about 15 Watts/gram. More preferably, the gravimetric power maximum of the device is greater than about 17 Watts/gram. Even more preferably, the gravimetric power maximum of the device is greater than about 20 Watts/gram. In some embodiments the gravimetric power maximum of the device is greater than about 26 Watts/gram.
According to an eleventh aspect of the invention there is provided a charge storage device including:
a first electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the volumetric power maximum of the device is greater than about 35 Watts/cm3.
According to a twelfth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
disposing a second electrode in opposition to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing within a sealed package the electrodes, the separator and an electrolyte, wherein the electrodes are immersed in the electrolyte; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the volumetric power maximum of the device is greater than about 35 Watts/cm3.
According to a thirteenth aspect of the invention there is provided a charge storage device including:
a first electrode;
a second electrode being opposed to and spaced apart from the first electrode;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the time constant of the device is less than about 0.03 seconds.
Preferably, the time constant of the device is less than about 10xe2x88x922 seconds. More preferably, the time constant of the device is less than about 10xe2x88x923 seconds. Even more preferably, the time constant of the device is less than about 10xe2x88x923 seconds. In some embodiments the time constant of the device is less than about 10xe2x88x924 seconds.
According to a fourteenth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode;
providing a second electrode being opposed to and spaced apart from the first electrode;
disposing a porous separator between the electrodes;
containing the electrodes, the separator and an electrolyte in which the electrodes are immersed a sealed package; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the time constant of the device is less than about 0.03 seconds.
Preferably, the time constant of the device is less than about 10xe2x88x922 seconds. More preferably, the time constant of the device is less than about 10xe2x88x923 seconds. Even more preferably, the time constant of the device is less than about 10xe2x88x923 seconds. In some embodiments the time constant of the device is less than about 10xe2x88x924 seconds.
According to a fifteenth aspect of the invention there is provided a charge storage device including:
a plurality of first sheet electrodes having respective first tabs extending therefrom;
a plurality of second sheet electrodes alternated with the first electrodes and having respective second tabs extending therefrom;
a porous separator means disposed between adjacent electrodes; and
a sealed package for containing the electrodes, the separator means and an electrolyte, whereby the first tabs are electrically connected to a first terminal and the second tabs are electrically connected to a second terminal, both the first and second terminals extending from the package to allow external electrical connection to the respective electrodes.
According to a sixteenth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a plurality of first sheet electrodes having respective first tabs extending therefrom;
alternating a plurality of second sheet electrodes with the first electrodes, the second sheet electrodes having respective second tabs extending therefrom;
disposing a porous separator means between adjacent electrodes;
containing within a sealed package the electrodes, the separator means and an electrolyte;
electrically connecting the first tabs to a first terminal and the second tabs to a second terminal, wherein both the first and second terminals extending from the package to allow external electrical connection to the respective electrodes.
According to a seventeenth aspect of the invention there is provided a charge storage device including:
a first sheet electrode;
a second sheet electrode disposed adjacent to the first electrode, whereby the electrodes are folded back upon their respective lengths;
a porous separator disposed between adjacent electrodes; and
a sealed package for containing the electrodes, the separator and an electrolyte, whereby the first electrode is electrically connected to a first terminal and the second electrode is electrically connected to a second terminal, both the first and second terminals extending from the package to allow external electrical connection to the respective electrodes.
According to an eighteenth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first sheet electrode;
disposing a second sheet electrode adjacent to the first electrode;
folding the electrodes are back upon their respective lengths;
disposing a porous separator between adjacent electrodes;
sealing within a package the electrodes, the separator and an electrolyte; and
electrically connecting the first electrode to a first terminal and the second electrode to a second terminal, wherein both the first and second terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a nineteenth aspect of the invention there is provided a multiple charge storage device including:
a first electrode being electrically connected to a first terminal;
a second electrode disposed adjacent the first electrode and being electrically connected to a second terminal;
a third electrode disposed adjacent to the first electrode and being electrically connected to the second terminal;
one or more porous separators disposed between adjacent electrodes; and
a package for containing the electrodes, the one or more separators and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twentieth aspect of the invention there is provided a method of manufacturing a multiple charge storage device, the method including the steps of:
providing a first electrode;
electrically connecting the first electrode to a first terminal;
disposing a second electrode adjacent the first electrode;
electrically connecting the second electrode to a second terminal;
disposing a third electrode adjacent to the first electrode;
electrically connecting the third electrode to the second terminal;
disposing one or more porous separators between adjacent electrodes; and
containing within a package the electrodes, the one or more separators and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twenty first aspect of the invention there is provided a multiple charge storage device including:
a package defining a sealed cavity containing an electrolyte;
two spaced apart capacitor terminals each extending between a first end located within the cavity and a second end external to the package;
a first capacitor cell located within the cavity and being in contact with the electrolyte, wherein the first cell has both a first predetermined time constant and two cell terminals which are electrically connected to respective capacitor terminals; and
a second capacitor cell located within the cavity and being both in contact with the electrolyte and maintained in a spaced apart configuration with respect to the first cell, the second cell having both a second predetermined time constant and two cell terminals which are electrically connected to respective capacitor terminals.
According to a twenty second aspect of the invention there is provided a method of manufacturing a multiple charge storage device including the steps of:
containing an electrolyte in a sealed cavity defined by a package;
providing two spaced apart capacitor terminals each extending between a first end located within the cavity and a second end external to the package;
locating a first capacitor cell within the cavity and in contact with the electrolyte, wherein the first cell has both a first predetermined time constant and two cell terminals which are electrically connected to respective capacitor terminals; and
locating a second capacitor cell within the cavity and in contact with the electrolyte while being maintained in a spaced apart configuration with respect to the first cell, the second cell having both a second predetermined time constant and two cell terminals which are electrically connected to respective capacitor terminals.
According to a twenty third aspect of the invention there is provided a multiple charge storage device including:
a first sheet electrode being electrically connected to a first terminal and having a first coating on at least one side thereof, the coating being of predetermined varying thickness;
a second electrode disposed adjacent to the first electrode and being electrically connected to a second terminal;
one or more porous separators disposed between adjacent electrodes; and
a package for containing the electrodes, the one or more separator and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twenty fourth aspect of the invention there is provided a method of manufacturing a multiple charge storage device, the method including the steps of:
providing a first sheet electrode;
electrically connecting the first electrode to a first terminal;
applying a first coating on at least one side of the first electrode, the coating being of predetermined varying thickness;
disposing a second electrode adjacent to the first electrode;
electrically connecting the second electrode to a second terminal;
disposing one or more porous separators between adjacent electrodes; and
containing within a package the electrodes, the one or more separator and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twenty fifth aspect of the invention there is provided a multiple charge storage device including:
a first sheet electrode being electrically connected to a first terminal and including a first coating on one side thereof and a second coating on the other side thereof, the first coating being of a first predetermined thickness and the second coating being of a second predetermined thickness;
a second sheet electrode being electrically connected to a second terminal and disposed adjacent to the one side of the first electrode, wherein the second electrode includes a third coating on one side thereof of a third predetermined thickness, the third coating being opposed to the first coating;
a third electrode being electrically connected to the second terminal and disposed adjacent to the other side of the first electrode, wherein the third electrode includes a fourth coating on one side thereof of a fourth predetermined thickness, the fourth coating being opposed to the second coating;
one or more porous separators disposed between adjacent electrodes; and
a package for containing the electrodes, the one or more separators and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twenty sixth aspect of the invention there is provided a method of manufacturing a multiple charge storage device, the method including the steps of:
providing a first sheet electrode;
electrically connecting the first electrode to a first terminal;
applying a first coating to one side of the first electrode and a second coating to the other side, the first coating being of a first predetermined thickness and the second coating being of a second predetermined thickness;
applying a third coating on one side of a second electrode, the third coating being of a third predetermined thickness;
disposing the second sheet electrode adjacent to the first electrode such that the third coating is opposed to the first coating;
electrically connecting the second electrode to a second terminal;
applying a fourth coating of a fourth predetermined thickness to a third electrode;
disposing the third electrode adjacent to the first electrode such that the fourth coating is opposed to the second coating;
electrically connecting the third electrode to the second terminal;
disposing one or more porous separators between adjacent electrodes; and
containing within a package the electrodes, the one or more separators and an electrolyte, whereby the terminals extend from the package to allow external electrical connection to the respective electrodes.
According to a twenty seventh aspect of the invention there is provided electrodes for use in a supercapacitor, the electrodes including:
a substrate; and
carbon particles mixed with a suspension of protonated carboxy-methyl-cellulose coated on the substrate.
According to a twenty eighth aspect of the invention there is provided a supercapacitor including:
at least one pair of electrodes having a mixture of carbon particles and a suspension of protonated carboxy-methyl-cellulose coated on facing surfaces of the at least one pair of electrodes;
a separator positioned between said facing surfaces of said at least one pair of electrodes; and
an electrolyte wetting the separator.
According to a twenty ninth aspect of the invention there is provided a charge storage device including:
a first electrode having a first layer formed from a non-foamed carbon;
a second electrode having a second layer formed from a non-foamed carbon, the second layer being opposed to and spaced apart from the first layer;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the surface area of the carbon used to form the first and second layers is greater than 20 m2/gram.
According to a thirtieth aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
coating a first electrode with a first layer formed from a non-foamed carbon;
coating a second electrode with a second layer formed from a non-foamed carbon;
opposing the first and second layers in a spaced apart configuration;
disposing a porous separator between the electrodes;
collectively containing the electrodes, the separator and an electrolyte in which the electrodes are immersed in a sealed package; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that the electrodes both extend from the package to allow external electrical connection to the respective electrodes, wherein the surface area of the carbon used to form the first and second layers is greater than 20 m2/gram.
According to a thirty first aspect of the invention there is provided a charge storage device including:
a first electrode having a first substrate and a first carbon layer supported by the substrate, the layer being formed from a carbon having a surface area of at least about 400 m2/gram;
a second electrode having a second substrate and a second carbon layer supported by the second substrate, the second layer being formed from a carbon having a surface area of at least about 400 m/gram, the second layer being opposed to and spaced apart from the first layer,
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric power maximum of the device is greater than about 4.8 Watts/gram.
Preferably, the surface area of the carbon is at least 1200 m2/gram. More preferably, at least one of the layers contains more than one type of carbon.
According to a thirty second aspect of the invention there is provided a method of manufacturing a charge storage device, the method including the steps of:
providing a first electrode having a first substrate and a first carbon layer supported by the substrate, the first carbon layer being formed from a carbon having a surface area of at least about 400 m2/gram;
providing a second electrode having a second substrate and a second carbon layer supported by the second substrate, the second layer being formed from a carbon having a surface area of at least about 400 m2/gram, the second layer being opposed to and spaced apart from the first layer;
disposing a porous separator between the electrodes;
containing the electrodes, the separator and an electrolyte in which the electrodes are immersed in a sealed package; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively such that both the terminals extending from the package to allow external electrical connection to the respective electrodes, wherein the gravimetric power maximum of the device is greater than about 4.8 Watts/gram.
Preferably, the surface area of the carbon is at least 1200 m2/gram. More preferably, at least one of the layers contains more than one type of carbon.
According to a thirty third aspect of the invention there is provided an energy storage device including:
a housing;
a first and a second opposed electrodes having respective first and a second charge storage capacities, the electrodes being disposed within the housing and the first charge storage capacity being greater than the second charge storage capacity;
a separator intermediate the electrodes; and
an electrolyte disposed within the housing for transferring charge with the electrodes.
Preferably, the first electrode includes an aluminium sheet having a first carbon coating on one side thereof and the second electrode includes an aluminiun sheet having a second carbon coating on one side thereof wherein the first and the second coatings are opposed. More preferably, the sheets are substantially dimensionally equivalent and the charge storage capacities vary due to differences between the first coating and the second coating. Even more preferably, the first coating is thicker than the second coating. In other embodiments, however, the specific capacitance of the first coating is greater than that of the second coating. That is, the first coating includes a carbon which provides a predetermined capacitance per gram, which is greater than that of the carbon included within the second coating. In further embodiments the difference in charge storage capacities is due to differences in the loading of the coatings, expressed in milligrams of coating per cm2, while in other embodiments it is due to differences in active surface area of the carbon per unit area of electrode.
Preferably, the charge storage capacities are different due to a difference in surface area of the first and second electrodes.
In a preferred form the ratio of the first charge storage capacity and the second charge storage capacity is in the range of about 9:7 to 2:1. More preferably, the ratio is in the range of about 5:3 to 2:1.
In a preferred form the difference in the first and second charge storage capacities is due to the second electrode including a filler material. In some embodiments this filler material is a lower surface area carbon, while in other embodiments use is made of metal fibres or carbon nano-tubes. More preferably, the filler material is conductive. Even more preferably, the first and the second electrodes ore of about the same nominal thickness notwithstanding the inclusion of the filler material.
According to a thirty fourth aspect of the invention there is provided a method of producing an energy storage device having a housing, the method including the steps of:
disposing within the housing a first and a second opposed electrodes having respective first and a second charge storage capacities wherein the first charge storage capacity being greater than the second charge storage capacity;
disposing a separator intermediate the electrodes; and
providing an electrolyte within the housing for transferring charge with the electrodes.
Preferably, the first electrode includes an aluminium sheet having a first carbon coating on one side thereof and the second electrode includes an aluminium sheet having a second carbon coating on one side thereof wherein the method includes the further step of opposing the first and the second coatings. More preferably, the sheets are substantially dimensionally equivalent and the method include the further step of providing differences between the first coating and the second coating to provide the variation in the charge storage capacities. Even more preferably, the first coating is thicker than the second coating. In other embodiments, however, the specific capacitance of the first coating is greater than that of the second coating.
According to a thirty fifth aspect of the invention there is provided a charge storage device including:
a housing;
a first sheet electrode disposed within the housing;
a second sheet electrode disposed within the housing adjacent to and opposed with the first sheet electrode;
a separator for enveloping substantially all of the first electrode and for maintaining the electrodes in a spaced apart configuration;
an electrolyte disposed intermediate the electrodes; and
two terminals extending from the respective electrodes and terminating outside the housing for allowing external electrical connection to the electrodes.
Preferably, the separator includes two opposed separator sheets which are connected along at least one common edge and the first electrode is disposed between the separator sheets. More preferably, the separator sheets are integrally formed. Even more preferably, the separator sheets are integrally formed along the common edge.
Preferably also, each separator sheet includes a first edge and a second edge spaced apart from the first, both of which extend away from the common edge. More preferably, each separator sheet also includes a third edge which extends between the first edge and the second edge, wherein the first edges are opposed and joined together and the second edges are opposed and joined together. Even more preferably, the third edges are opposed.
In a preferred form, the first electrode includes a first sub-sheet and a second sub-sheet which is opposed to the first. More preferably, the first and the second sub-sheets are opposed. Even more preferably, each of the first and second sub-sheets are joined along a common edge. Preferably also, the common edge between the first and second sub-sheets is disposed adjacent to the common edge between two opposed separator sheets.
According to a thirty sixth aspect of the invention there is provided a method of constructing a charge storage device having a housing, the method including the steps of:
disposing at least two opposed sheet electrodes within the housing;
enveloping substantially all of a first one of the electrodes with a separator for maintaning the electrodes in a spaced apart configuration;
disposing an electrolyte intermediate the electrodes; and
providing two terminals extending from the respective electrodes and terminating outside the housing for allowing external electrical connection to the electrodes.
Preferably, the separator includes two opposed separator sheets connected along at least one common edge and the method includes the further step of disposing the first electrode between the separator sheets. More preferably, the separator sheets are integrally formed. Even more preferably, the separator sheets are integrally formed along the common edge.
Preferably also, each separator sheet includes a first edge and a second edge spaced apart from the first, both of which extend away from the common edge. More preferably, each separator sheet also includes a third edge which extends between the first edge and the second edge, wherein the method includes the further step of joining together the first edges and joining together the second edges. Even more preferably, the third edges are opposed.
According to a thirty seventh aspect of the invention there is provided a charge storage device including:
two opposed electrodes having respective coatings of carbon particles, the particles having a predetermined nominal diameter and the coatings having of a thickness greater than but in the order of the nominal diameter;
a porous separator disposed between the electrodes;
a sealed package for containing the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
a first terminal and a second terminal being electrically connected to the first electrode and the second electrode respectively and both extending from the package to allow external electrical connection to the respective electrodes.
Preferably, the predetermined nominal diameter is less than about 8 microns and the coating thickness is less than 100 microns. More preferably, the predetermined nominal diameter is less than about 6 microns and the coating thickness is less than about 36 microns. Even more preferably, the predetermined nominal diameter is less than about 2 microns and the coating thickness is less than about 6 microns.
According to a thirty eighth aspect of the invention there is provided a method of manufactuning a charge storage device, the method including the steps of:
opposing two electrodes having respective coatings of carbon particles, the particles having a predetermined nominal diameter and the coatings having of a thickness greater than but in the order of the nominal diameter;
disposing a porous separator between the electrodes;
containing in a sealed package the electrodes, the separator and an electrolyte in which the electrodes are immersed; and
electrically connecting a first terminal and a second terminal to the first electrode and the second electrode respectively for extending from the package to allow external electrical connection to the respective electrodes.
Unless the context clearly requires otherwise, throughout the description and the claims, the words xe2x80x98comprisexe2x80x99, xe2x80x98comprisingxe2x80x99, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of xe2x80x9cincluding, but not limited toxe2x80x9d. Additionally, the words xe2x80x98includesxe2x80x99, xe2x80x98includingxe2x80x99 and the like are used interchangeably with the words xe2x80x98comprisexe2x80x99, xe2x80x98comprisingxe2x80x99, and the like.